New Scientist: Vaccine scandal revives cancer fear

Many millions more people than previously thought might have been given polio vaccine contaminated with a monkey virus linked to cancer. It has been known since 1960 that early doses of polio vaccine were widely contaminated with simian virus 40, or SV40, which infects macaque monkeys. Tens of millions of people in the US and an unknown number in other countries, including the UK, Australia and the former Soviet Union, may have been exposed prior to 1963.